Auditory rhythm has a long history of use for affecting neurological function, with the earliest uses being documented tens of thousands of years ago. These original techniques are some of the most pervasive therapeutic practices known to man, existing on every continent even among people who had no contact with one another (Harner, 1990). As an ethnomusicologist I was fascinated by the commonality in the techniques within such disparate cultures. I spent over a decade trying to understand how the same basic therapeutic approaches developed when so many other aspects of these societies were vastly different.

The answer, it appeared, was that the physiological mechanisms at work are so powerful that experimentation by each culture resulted in a common finding: You can affect consciousness, cognition, and behavior by employing only two specific rhythmic techniques. One consists of a repetitive pulse while the other employs complex rhythmic structures.

Discovering such commonality among traditional therapeutic rhythm practices prompted another, perhaps more important, question: Can these therapeutic effects sustain themselves outside of the cultural context in which they developed? I believed so, but many of my colleagues did not, believing instead that the rhythm was secondary to the rituals they were imbedded in (and is often attributed to the placebo effect). This led to an odyssey that began in 1992 and has continued to this day, culminating in the development of Rhythmic Entrainment Intervention™ (REI).

REI is a music-medicine therapy (Spintge & Droh, 1992) that stimulates and synchronizes the listener's brain. REI is available as some generalized CDs (Calming Rhythms, Focusing Rhythms and the SI Series CDs), several Semi-Custom Programs and the REI Custom Program™. This is a custom-made, 10-week program that optimizes neurological function.

Auditory Driving

As I developed REI, my first step was to identify the core mechanisms of the traditional techniques. It turns out that these mechanisms are simple, powerful, and easily understood. First, human consciousness can be directly affected by an auditory stimulus. This is called "auditory driving" (Goldman, 1992). Auditory driving states that a listener's brain wave activity will synchronize with the pulsation of an auditory rhythm (provided certain conditions are met).

Traditional practitioners would employ a four-beat-per-second rhythm, which would in turn facilitate a corresponding four-beat-per-second pulsation in the listener's brain, resulting in bilateral neurological synchronization and a shift in consciousness to a theta state (this is a meditative state)(Maxfield, 1994). With REI we double the tempo to synchronize a listener's brain into a relaxed neurological state called alpha. This is the state of consciousness where sensory processing is optimized.

Complex Rhythms

The second core mechanism involved in traditional therapeutic rhythm techniques consists of using complex rhythms to activate the brain (Scartelli, 1987; Shatin, Koner, Douglas-Longmore, 1961; Parsons, 1996). Here complex auditory rhythms stimulate the Reticular Activating System (RAS), a part of the brain that controls sensory input (Scartelli, 1992). Applying rhythm - especially complex rhythm – to activate the brain is one level of the stimulation provided by REI. As we conducted research we discovered another dimension to the rhythms: One that appears to be more important than just complexity. It seems that each rhythm produces a different response.

Once the core mechanisms were discovered the next step was to determine the best way to deliver the correct stimulus to aid in the areas in which I was interested. Traditional practitioners performed the rhythms live for each person and adjusted their rhythms based upon the responses they saw in their patient.

Daily Listening for Long-Term Change

This is where I started -- the first 1,000 people that REI was used for experienced this one-on-one, live stimulus. They also listened to a recording of one of their live sessions daily in their home. Daily listening was a departure from the traditions, but I felt that people needed the stimulation repeated consistently for a length of time in order for any long-term change to be expected.

One of the first children that I worked with in this manner was a seven-year-old girl on the autism spectrum. In this case, the girl, let's call her Stephanie, was referred to me because of extreme anxiety. This anxiety impacted every aspect of her life: She wasn't able to sleep in her own room and needed to be in constant contact with her mother; transitions and even minor changes in her environment were a point of crisis for her throughout the day.

She also had significant language and social delays. Her language consisted largely of repeating rote words and phrases. Although she had a large vocabulary, she was unable to communicate beyond her basic needs and desires. Socially, she lacked eye contact and wasn't able to interact appropriately with her peers.

She calmed down within minutes during the first live session, and after the second session she remained calm and was able to sleep in her own room from that night on. Stephanie listened to a recording of her third live session everyday for eight weeks. At seven weeks she spontaneously described events in proper sequence for the first time. She was also developing social connections and had begun making friends.

She was mainstreamed at school (she was in a classroom with non-autistic children and had a one-on-one aide) and at 10 weeks the school psychologist evaluated Stephanie in her classroom and noted that she was "indistinguishable from the "normal" children in the class." She continued listening to her recording for several more months and eventually no longer required her one-on-one aide.

Universal Calming Effects

This, and many other cases studies, led to a formal study conducted in a public school setting (Strong, 12). This study consisted of 16 children from age 6 to 12 who were on the autism spectrum. The results of this study showed almost universal calming effects (only one child was not calm most of the time, and this child ended up not being on the autism spectrum).

Long-term change was significant for anyone who heard the recording at least four times per week. This study caught the attention of several prominent autism professionals and led to a paper of this study being presented at several professional research conferences (including one organized by The Center for the Study of Autism led by Dr. Stephen Edelson, who went on to design all of our double-blind, placebo-controlled studies).

At this point my interest in exploring the therapeutic application of auditory rhythmic stimulation techniques deepened. I formed the REI Institute with Beth Kaplan with no intention of creating a "therapy" that would be available outside of a research environment. Our goal was simply to try to understand how auditory rhythmic could be used to enhance neurological function.

Over the next 10 years the REI Institute conducted numerous studies and presented dozens of scientific papers on what we were learning. Two of the key discoveries of this period were that synchronization was universal when certain techniques were applied and that each rhythm used elicited a definite, observable response over time.

Specific Rhythms' Observable Effects

In other words, we found that we could introduce specific rhythms to have a pre-determined effect on each listener. To date, we have documented over 600 rhythms that seem to correspond to symptoms and combinations of symptoms. As a result we found it was critical to use just the right rhythms for each person in order to have the greatest positive benefits for that person.

During the 1990s, the REI Institute conducted a series of double-blind, placebo-controlled studies to try to understand the best approaches to take in balancing auditory stimulation and synchronization. What we learned in a nutshell was that the custom-made CDs are more effective than CDs created for a broad user base.

Custom-made, Revisable CDs

This leads to the second unique aspect of REI: The REI Custom Program™ is custom-created for each person based on his unique characteristics. By custom-making each CD we can ensure that the correct level of stimulation is used for that person. In the event that we aren't seeing the results we've come to expect, we also revise the CDs until we see the results we are looking for. The practice of revising the custom-made CDs is the third unique aspect of REI.

Because the REI Custom Program™ is created for each person, we are able to focus the CDs on the three or four main issues someone faces. As a result, everyone responds differently to his CDs, but we see the most significant benefits in some general categories. These include anxiety, sleep, self-stimulatory behaviors, language skills, sensory sensitivities and defensiveness, socialization, attention and focus, and aggressive or oppositional behaviors.

Another example of the results with the REI Custom Program™ (and one most relevant to this article) can be seen with a 10-year-old boy with severe sensory issues. Gerald, as I'll refer to him, saw significant improvement within just a few days. Before he began the REI Custom Program™ he refused to wear shoes or socks, covered his ears whenever music was played, couldn't tolerate headphones, and socially isolated himself from others, often retreating to a dark, quiet room.

Within the first week of listening to his CDs, Gerald was more tolerant of everyday sounds. He also spontaneously joined his extended family outside and began interacting with them. By the second week he was interacting with his siblings and cousins much more frequently, and by week four, according to his REI Provider, "... He is wearing socks and tennis shoes every day. He now not only allows mom to listen to music in the car, he often goes to his room and 'rocks out' to his own pop music. He has been more interactive and engaged in activities as well as initiating appropriate play with other children."(Strong, 1996) He was also able to tolerate headphones for the first time.

Open-Air Environment

This leads to the fourth thing that distinguishes REI from other auditory programs: REI is designed to be used in an open-air environment. That is, we don't use headphones for the implementation of the therapy. The CDs simply need to play quietly in the background once a day (with the exception of the third week where the CDs are used twice a day). Having the stimulus in the background while the rest of the sensory input of life goes on forces the brain's RAS to work hard to decipher the pattern in the stimulus while also ensuring that the listener doesn't become over-stimulated by the rhythms.

In 2004 we began offering REI Custom Program™ through trained providers -– we now have hundreds across the U.S. This represented a monumental shift after 22 years of research -- research that simply started from my desire to understand why traditional therapeutic rhythm practices were so prevalent around the world.

In spite of our growth and the expansion of REI beyond just research, I am still personally involved in the creation of all the REI Custom Program™ CDs that leave our office and am still impassioned by learning more about how auditory rhythmic stimulation can impact individuals with neurological issues.